1. Technical Field Embodiments of present disclosure are directed to a laser apparatus.
2. Discussion of the Related Art
In general, methods of crystallizing an amorphous silicon layer into a polycrystalline silicon layer include solid phase crystallization (SPC), metal induced crystallization (MIC), metal induced lateral crystallization (MILC), excimer laser annealing (ELA), etc. In particular, to manufacture an organic light emitting diode (OLED) display or a liquid crystal display (LCD), the excimer laser annealing (ELA) method uses a laser beam to crystallize an amorphous silicon layer into a polycrystalline silicon layer.
A laser apparatus used in an excimer laser annealing (ELA) process includes a laser generator that generates a source laser beam. The source laser beam is a first laser beam has a rectangle shaped cross-section thereof with a long axis and a short axis. The source laser beam typically has an Gaussian energy distribution in both the long axis direction and the short axis direction. The Gaussian distribution is a normal distribution that has left and right symmetry with respect to an average.
However, shaking may be generated between a plurality of laser shots, which can alter the energy distribution of the source laser beam to deviate from the normal distribution, thereby causing a left/right asymmetry. In this case, crystallization defects may be generated in the polycrystalline silicon layer.